PCR for differentiation of mrp variants (A) and detection of MRP variants by anti-MRP Western blot (B) in the indicated S. suis strains. V2310/1 (mrp); #451 (mrp*); D14412/3 (mrp***); 13-00283-02 (mrp****); mrp reference strains: D282 (mrp); A3286/94 (mrp*); 90-2741-7 (mrp***); V7353/1 (mrp****); T15 (mrp negative reference strain). Strain 10 and the isogenic mrp-mutant 10M7  served as MRP references in the Western blot. MW, 100 bp plus ladder (Invitrogen). Sizes of the PCR products (base pairs) and of the MRP variants (kDa) are indicated on the left. The Western blot was conducted using culture supernatant (C) and protoplast supernatant (P) as samples.